The present invention is of particular importance when used in a cable-based network for distributing video, digital, and conventional telephony signals, and that application will be described in detail herein. However, the basic concepts of the present invention have broader application to other networks or systems where power disruption at remote sites can cause significant problems; several such networks and systems will be briefly described below to illustrate the scope of the present invention. Accordingly, the scope of the present invention should be determined with reference to the claims appended hereto rather than the following detailed description.
The basic technology currently exists to provide broadband digital communications capabilities to the mass market. However, the use of broadband digital communications networks at this time is largely limited to point to point networks designed for large commercial customers. This is because the communications infrastructure available to serve small commercial and residential customers is comprised largely of twisted pair wire for carrying analog telephone signals and/or coaxial cable for carrying analog television signals. This infrastructure as currently implemented does not allow two-way, broadband digital communications
It is anticipated that, eventually, the mass market will be served by a broadband communications network based on fiber optic cable. However, substantial time and money will be required to replace the twisted pair wire and coaxial cable infrastructure currently serving the end customer with a fiber optic infrastructure. Accordingly, a fiber optic based communications system may not be available to the mass market for some time.
In the meantime, plans are being made for broadband communications networks based on a hybrid solution in which fiber optic cable is used as a backbone to carry signals to the twisted pair and coaxial cable currently serving the end user. The fiber optic portion of such a network can then be expanded incrementally throughout the distribution plant until it eventually extends to the end user.
As the point at which such a hybrid network is converted from fiber optic cable to coaxial cable and/or twisted pair wire extends outwardly from the central office to the end user, problems with disruption of the system caused by power outages similarly become decentralized. The existing telephony solutions to power outages are not applicable to providing power to coaxial cable networks. Further, the standards for preventing disruption of services in cable TV networks are not as stringent as those for basic communications services. While disruption of cable TV transmission caused by a power outage is not a major problem, the problems caused by disruptions to a communications system can be severe. The existing solutions for providing emergency power in coaxial cable networks are thus also inadequate because they are not designed to meet the higher standards required for preventing disruptions of basic communications systems.
The need thus exists for a system for generating emergency power signals that can be used in a hybrid fiber optic/coaxial cable based communications system and which meets the standards required for preventing disruptions of basic communications systems.